Trench wall retainer



F. COTE TRENCH WALL RETAINER Filed Dec.

Jan' 167 @aired States Patent G 3,016,714 'FRENCH WALL RETAINER Felix Cote, 10562 Waverley, Montreal, Quebec, Canada Filed Dec. 1, 1958, Ser. No. 177,449 2 Claims. (Cl. 61-41) The present invention relates to a safety trench wall retainer, and more particularly to a retainer so constructed as to be easily movable.

Safety regulations in construction work do not allow the men to work at the bottom of deep trenches unless there is provided a means for retaining the trench walls, to prevent their sliding in on the men. Wall retainers for this purpose, employed hitherto, comprise in general two rectangular plates held apart by a plurality of braces, so as to provide an open box unit, in which the men can work in safety. As the work progresses it becomes necessary to move the unit, and for this purpose the Wall retainer is usually lifted out with a mechanical shovel, by means of cables, and dropped at its new location. It is impractical to slide the retainer, because too much friction is developed by its edges engaging the rough surface at the bottom of the trench.

The present invention obviates the disadvantages of conventional, rectangular trench wall retainers, by providing a retainer the walls of which are in the shape of polygons having' at least tive sides; according to the invention any polygon of live sides or more may be used, up to the limit defined by a circle. Such a retainer need not be lifted and dropped again, when it is required to move it, but may instead be rolled forward to its new location by pulling on it with a tractor or a mechanical shovel. If the walls of the retainer are in the form of polygons having a limited number of sides, the unit will rest stably on one side, and when it is moved, it will pivot about the bottom apex closest to the pulling device, and will again come to rest on a side adjacent to that on which it was resting.

in practice hexagons to octagons are preferably used, since these figures best define the intervals at which the retainer must be moved. The two walls have their corresponding sides lying in the same plane, and according to a preferred feature of the invention telescopic braces are provided, so as to enable adjusting of the width of the unit, according to the width of the trench in which it is used.

Further objects and features of the present invention will become apparent from the following description of two embodiments thereof, taken in conjunction with the accompanying drawings, wherein like reference characters indicate like elements throughout, and in which:

FIG. 1 is a perspective view of a wall retainer, used in conjunction with laying of pipe, and shown in operative position in a trench;

FIG. 2 is an end view of the wall retainer of FIG. 1;

FIG. 3 is a vertical section longitudinally of the trench, taken on line 3-3 of FIG. 2, and showing the hexagonal form of the walls, and the manner in which the unit is moved;

Patented Jan. 16, 1952 ICC FIG. 4 is a partial section, on an enlarged scale, taken on line 4-4 of FIG. 3, and showing a reinforcing member of the wall retainer; and

FIG. 5 is a side view of a second embodiment having octagonal sides.

With reference to FIGS. 1, 2 and 3, each wall 10 of the wall retainer comprises a hexagonal steel plate 11 which is reinforced by a framework of steel channels 12 disposed on the sides and the diagonals of the hexagon. As shown in FIG. 4, the channels 12 have their open side adjacent and welded to the steel plates 11.

Walls 10 are spaced apart by a central telescopic brace 13, the two parts of which are adjustably secured together by means of bolts 14, and by six smaller telescopic braces 15, bearing against the reinforcing channels 12, and also adjustably secured together by means not shown. The spacing of the two walls 10 can thus be adjusted to suit the trench width.

FIG. 3 shows the manner in which the wall retainer is moved. As shown in the tigure the unit is resting on side 16. When it is desired to move it, a cable is attached to any one of braces 15, but preferably to one of the upper ones, and the entire unit is pivoted about apex 17, as shown by the arrows, until it cornes to rest on the side 18, taking up the position shown in the ligure in dotted lines.

FIG. 5 shows a retainer with octagonal walls 19, and wherein the side displacement is shorter than in the hexagonal retainer of FIGURES l to 3.

The embodiments illustrated and described are given only by way of example, and various modifications are possible within the spirit and scope of the appended claims.

I claim:

l. A shield for a trench adapted to protect workers working in said trench comprising a pair of walls and braces connecting said walls and forming therewith a rigid self-supporting unit, the spacing of said walls being substantially smaller than the space between the sides of said trench and said walls being in the .shape of polygons having at least five sides.

2. A shield for a trench adapted to protect workers working in said trench comprising a pair of walls and adjustable braces connecting said walls, and forming therewith a rigid self-supporting unit, said braces being adjusted to provide a spacing of said walls essentially smaller than the space between the sides of said trench and said walls being in the shape of polygons having at least tive sides.

References Cited in the file of this patent UNITED STATES PATENTS 2,188,077 Dowd Jan. 23, 1940 2,777,294 Rosa et al. Jan. 15, 1957 FOREIGN PATENTS 565,847 Great Britain Nov. 30, 1944 

